Firing on cylinders 2 and 4

[qwqb]

Hey Guys,

After a few months of my bike running well, it's not suffering from a lack of power. Turns out that it is only running on cylinders 2 and 4. For anyone who's interested, my method for testing this was to touch a wet cloth to the headers and listen to which ones sizzle!

In any case, I find it odd that its running on one cylinder from each coil. Im curious as to what sort of insight you guys might have. I will be replacing the spark plugs tonight as they do look a bit fouled. Thanks!

[Katarat]

If the bikes been sitting with old gas in it or the tank is rusty, Id suspect some clogged pilot jets if you know the spark plugs are good

[qwqb]

The bike did sit thru the winter but I did put some stabil in the tank beforehand, and let it run a while to make sure it got into the carbs.

I did a complete teardown and cleaning of the carbs about a year ago, but perhaps they need to be gone through again. thank you!

[mike_of_bbg]

There's lots of things it could be. Fouled plugs sounds like rich running - be it too much fuel or not enough air. Do 1 & 3 get hotter off idle? When was the last time you had a vacuum sync done?

[BassCliff]

Hi,

Test the plugs themselves. Or just replace them, they're cheap enough. It could be bad plugs or bad plug caps. It could be fouled carbs. See what's in the float bowls.


Thank you for your indulgence,

BassCliff

[azr]

It's crazy what I've done to a bike to only replace a plug and everything is working fine again. Start with the easiest.

[qwqb]

Thanks for the input guys. Whaddya know, after new plugs it runs like a champ! Now to fix my rich issue so I don't foul out anymore plugs

[qwqb]

I'm back with a little follow-up. The bike ran well for a day but the plugs are black as can be again and its back to stumbling. I'm wondering how I can tell if the bike is really running that rich, or if I'm getting oil in the cylinders?

[mike_of_bbg]

Can you post pics of your plugs? Are the insulators sooty? Oil would be shiny black IIRC.

Make sure your air filter is not over-oiled, and that there are no other restrictions in the air path. Check your voltage at the coils. Have you tested your coil secondaries and the plug boots? They often fail with high resistance.

[azr]

Hey qwqb. Glad you're still trying to work the bugs out but I noticed you keep posting different threads for the same basic problem. It's hard for us to help diagnose without seeing what you've already tried. Best to stick to one thread to avoid getting repeats of what someone else has already said as well hard to know what advise you have taken and tried. It does sound like (from reading multiple posts in your history) that you have a problem with jetting and possibly an electrical problem, ignitor problem maybe, not sure what ever came out of that thread.